Drafting machine



Nov. 2-6, 1963 w. PIEPER DRAFTING MACHINE Filed Mau-ch 25. 1959 2 Sheets-Sheet 1 /N'VE/v TOR:

Wi. l l. Pie per M@ AGENT NOY. 26, 1963 w, P|EPER 3,111,763

DRAFTING MACHINE Filed March 25, 1959 2 Sheets-Sheet 2 INI/EN TOR:

Willi. Pieper AGEN r United States Patent O 3,111,763 DRAFTING MACHlNE Wiili Pieper, Seestrasse 71, Kilchberg, Switzerland Filed Mar. Z3, 1959, Ser. No. $411,263 7 Claims. (Cl. 33-79) The present invention relates to a drafting machine with wheels arranged at the joints of its linkage, these wheels being interconnected in pairs by flexible pull bands in order to attain parallel displacement of a drafting square.

In the well-known drafting machines of this type, the wheels are connected to each other in pairs frictionally and rotatably. However, this frictional engagement of bands and wheels involves serious risks since, especially in the case of hard snapping of the drawing head into another swiveled position, it may happen that the bands slip on the wheels whereby the straightedges of the drafting equare, on being swiveled back into a previously indexed position, no longer occupy a position corresponding to the former initial position, so that the drafting machine must be re-adjusted. t

In order to obviate these drawbacks, attempts have already been made to interconnect pull bands and wheels in a positive manner by providing the wheels on their periphery with radially projecting pins and suitably perforating the pull bands whereby the projecting pins engaged corresponding holes of these bands. However, particularly on drafting machines arranged on upright drawing boards, it has been found that, because of the continually repeating engagement of the pins, the perforations in the bands become worn in the course of time, thus leading to inaccuracies which prevent exact working with the drafting machine.

The drafting machine according to the invention differs from these known machines in that the wheels of each pair are interconnected by two open-ended pull bands, one end of each pull band passing clockwise and the other end passing anticlockwise round a respective wheel and being firmly connected thereto.

With this design the drivers connecting the pull bands to the wheels never come out of engagement with the bands, so that there can be no play between band and wheel at the connecting point and, therefore, no substantial wear even after very long service.

In the case of a drafting machine according to the invention, the drawing head is preferably not arranged under the neighboring band wheel but is axially offset from it and is connected by means of a projecting arm to a driving disk coaxial with the said band wheel, the driving disk being able to be put into and out of rotatable relationship with the band wheel as desired.

This construction makes it possible to have a so-called base displacement, i.e. a changing of the fundamental position of the drawing head together with the drawing square. A further advantage of the mentioned construction is also to be found in the circumstance that the drawing squares be swiveled round the drawing-head axis through a much greater range, whilst otherwise, with the drawing head arranged under the band disk, the vertical arm of the drawing straightedge comes to lie under the parallel-motion linkage even with the slight anticlockwise swiveling, and thus becomes practically useless.

Further it is preferable for the band wheel arranged at the anchoring-support end of one arm of the parallelmotion linkage to be tiltable, and for this purpose to be swingable round an axis parallel to the plane of the drawing table and to the wheel itself. This construction makes it possible to remove the whole drafting machine from the drawing board without any risk of bending the linkage, or to swivel it aside round the anchoring support.

Further, the anchoring support consists preferably of 3,111,763 Patented Nov. 26, 1963 ICC two interconnected parts, one of which is engageable with the drawing board while the other is pivotally coupled with the associated band wheel, one part being rotatably adjustable with respect to the other part round an axis at right angles to the plane of the drawing board and adapted to be indexed in various relative positions.

This construction enables the parallel-motion linkage to be set with respect to the drawing board in such a manner that an optimum drawing-board surface can be passed over by the drawing square.

One embodiment of the invention is represented by Way of example in the drawing, wherein:

FIG. l shows a top view of a drafting machine according to the invention,

FIG. 2 is a partial top view of the same, with its carrier displaced with respect to the anchoring support thereof;

FIG. 3 is a fragmentary longitudinal cross-sectional view of the drafting machine taken on the line III-III in FIG. 1, drawn to a larger scale;

FIG. 4 is a fragmentary longitudinal cross-sectional view of the drafting machine taken on the line IV-IV in FIG. 1, also drawn to a larger scale;

FIG. 5 shows a partial top View of the machine in a position swiveled to the front; and

FIG. 6 is an axial sectional view of a part of the machine.

`In the drafting machine shown, the parallel-motion linkage has as usual two arms A, B articulated to each other, one arm being connected to the anchoring support 15, 16 serving to fix it to the drawing board, the other carrying the drawing head 17 with the dnawing square 17a, 17h. The parallel motion linkage is formed by tubes 9, 10' arranged in parallel pairs, the tubes having ltheir ends inserted into casings 11, 12, 13, 14. In these casings, wheels 1, 2, 3y and 4 are rotatably mounted, the Wheels of each pair 1, 2 or 3, 4 :being connected to each other by two open flexible pull bands 5, 6 or 7, 8, respectively, in such a way that one end is passed clockwise while the other end is passed ranticlockwise round a respective wheel and firmly connected to it, for instance by screwing, riveting, welding etc. At 23a there are shown threaded sleeves arranged between the wheel casings 12, 14 and the tubes 9, 10, these sleeves enabling the pull bands S, 6 and 7, S to be stretched in such a manner that they always remain under tension even in the position of rest and/ or when the drafting machine is lying horizontal. The two pull bands of each pair of wheels 1, 2 or 3, 4 are arranged in four parallel planes A--A, B-B, C-C, D-D, the wheels having a separate groove 1a, 1b, 2a, 2b, 3a, 3b and 4a, 4b `for each fband. The pull bands 5', 6 and 7, 8 run in the tubes 9 and 1d' which protect the bands from mechanical interference and, as mentioned, serve as spacing means for the articulations of the parallel-motion linkage. The wheels r2., 3 mounted at the pivotal junction of the two arms A, B are rigidly interconnected or formed as one double wheel which is provided with four co-axial and parallel grooves 2a, 2b and 3a, 3b.

The ends of each band, as clearly seen in FIGS. 1 and 2, embrace the corresponding wheels over an arc well in excess of 180; one of the fasteners located at these ends is shown at 31 in FIG. 4. It will be seen that, by virtue of this arrangement, each of the arms A, B can be swung through an angle greater than to either side of the normal position shown in the drawing.

The drawing head 17 is axially offset from the neighboring band wheel 1 and connected by means of a projecting holding arm 18 with a driving disk 19 which lies coaxial with the band wheel 1 and is provided on the side facing the wheel 1 with a tapering recess 19a into which projects a clamping cone 1c integral with the band wheel 1. By means of this clamping cone, the driving disk 19 at the proximal end of holding arm 18 can be brought as desired into or out of rotary engagement with the band Wheel ll. For this purpose, adjustment means are -provided which enable the driving disk 19* to be slightly displaced axially with respect to the band wheel 1, in order to lbe able to bring the driving disk 19' into fric.ional engage-` ment with the clamping cone 1c or to disconnect the disk from the cone.

In `the lillustrated example, these adjustment means consist of an axle 'bolt 2d which passes through the hollow Shaft 27 carrying ya ball bearing 26 and is anchored at the lower end in a disk 25 engaging 'the driving disk 19 from. below, whilst at the upper end of the axle bolt 24 an eccentric lever 23 is swingable round a bolt 23 for contact with a ring 32 which rests on the shaft-supported race of Iball bearing Z6 as clearly shown in FIG. 6.

For establishing a clamping connection between the parts 1c and 19, the eccentric lever 23 is moved in the direction shown in FIG. 6 by the arrow F to displace the bolt 24 axially with respect to the tubular shaft 27, whilst the clamping connection is again disengaged when the lever 23 is moved `back again. A spring may be, provided which tends to keep the clamping cone 1c and the driving .disk 19 apart from each other in the disengaged position.

The band `wheel d arranged at the anchoring-support end of arm B is integral with a carrier plate 2c which is articulated to the anchoring support 16 by means of a pivotal axle 21 lying parallel to the plane of the band wheel 4 and of the drawing board.

The lower part 15 or the anchoring support is engageable with the drawing board, whilst the other upper part 16 thereof, is articulated to the carrier plate 2d. The part 15 of the anchoring support in its turn can be rotatably adjusted with respect to the other par-t 16 round a stud 22 at right angles to the plane of the drawing board and held in notches Si) for indexing it in diierent angular positions relative part 15. This possibility of rotary adjustment enables the drafting machine to be fixed on the drawing board in such a Way that the greatest possible drawing board surface can be passed over with the drawing head.

The presence of the pivot 21 then enables the whole drafting machine to be removed from the drawing board without any risk of bending its linkage, or to be swiveled aside round the anchoring support 15, 16.

After disengagement of the driving disk 19 from the clamping cone 1c, the whole drawing head together with the drawing square can be swiveled round the axis E-E of the band wheel 1, and thus the fundamental position of the drawing head and of the drawing square can be altered as desired. The axial d-isalignment of the drawing head 17 with respect to the band-wheel axis E-E, due to its mounting on the distal end of lever arm 1S, prevents the vertical 4arm ll'ia of the drawing square from coming to lie under the parallel-motion linkage A, B, even when swiveled slightly to the left, i.e. anticlockwise, under the control of head 17 as is Well known per se.

The casing 11 surrounding the band wheel 1 can be provided with a graduated disk by means of which the momentarily desired angle of rotation of the driving disk 19 and therefore also oi the drawing head 17 with respect to the band wheel 1 can be read or adjusted. instead of the frictional engagement between the band wheel 1 and the driving disk 19, a positive connection, for instance in the form of a notched disk, may be selected.

What I claim is:

1. A drafting machine comprising a parallel-motion linkage including two articulated arms each provided at its ends with a respective wheel of a pair thereof assigned to each of said arms, the wheels at the junction of said arms forming a rigid unit about whose axis said arms are independently swingable, link means on each arm interconnecting the wheels thereof for rotation in unison relative to the arm, anchor `means secured to the free end of one of said arms and engageable with a support for said linkage, and connecting means for securing a drawing accessory to the free end of the other of said arms; each of said link means comprising a pair of open-ended bands having its ends wound in opposite senses around the respective wheels, said bands being wound oppositely about each wheel while subtending angularly overlapping arcs thereof in a normal position of said linkage, and fastening means iirimly securing the two ends so wound around each of said wheels thereto at axially separated locations angularly odset in the sense of winding of said ends.

2. A drafting machine comprising a parallel-motion linkage including two articulated arms each provided at its ends with a respective wheel of a pair thereof assigned to each of said arms, the wheels at the junction of said arms forming a rigid unit about whose axis said arms are independently swingable, link means on each arm interconnecting the wheels thereof for rotation in unison relative to the arm, anchor means secured to the `free end of one of said arms and engageable with a support for said linkage, and connecting means for securing a drawing accessory to the free end of the other of said arms; each of said link means comprising a pair of open-ended bands having its ends wound in opposite senses around the respective Wheels, said bands being wound oppositely about each wheel, and fastening means iirmly securing the two ends so wound around each of said wheels thereto at axially separated locations, the two ends of said bands wound about each of said wheels each extend over an arc greater than in a normal position of said linkage.

3. A drafting machine according to claim 2 wherein each of said wheels is provided with a pair of axially spaced parallel circumferential grooves accommodating the respective bands.

4. A drafting machine according to claim 2 wherein said connecting means includes an elongated element extending perpendicularly to the axis of the wheel at the free end of said other arm, and adjusting means for selectively iixing the proximal end of said element to the lastmentioned wheel in different relative angular positions, the distal end of said element being provided with angular control means for selectively positioning said accessory on said element in different angular positions relative thereto.

5. A drafting machine according to claim 4 wherein said element terminates at said proximal end in a disk provided with a tapering surface formation, said lastmentioned wheel being provided with a complementary formation frictionally engageable therewith, said adjusting means further including pressure means for releasably urging said formations against each other.

6. A drafting machine according to claim 5 wherein said surface formation is a conical depression in said disk.

7. A drafting machine according to claim 5 wherein said last-mentioned wheel is provided with a tubular shaft, said pressure means comprising a bolt passing through said shaft and engaging said disk at one end, and a clamping lever coupled with the other end of said bolt for axially displacing it with respect to said tubular shaft.

References Cited in the le of this patent UNITED STATES PATENTS 1,360,496 Butterfield Nov. 30, 1920 1,408,252 Bieuville Feb. 28, 1922 2,164,217 Little June 27, 1939 2,178,045 yLittle Oct. 31, 1939 2,518,902 King Aug. l5, 1950 2,990,728 Wallace Aug. 25, 1959 FOREIGN PATENTS 514,040 France Nov. 8, 1920 

2. A DRAFTING MACHINE COMPRISING A PARALLEL-MOTION LINKAGE INCLUDING TWO ARTICULATED ARMS EACH PROVIDED AT ITS ENDS WITH A RESPECTIVE WHEEL OF A PAIR THEREOF ASSIGNED TO EACH OF SAID ARMS, THE WHEELS AT THE JUNCTION OF SAID ARMS FORMING A RIGID UNIT ABOUT WHOSE AXIS SAID ARMS ARE INDEPENDENTLY SWINGABLE, LINK MEANS ON EACH ARM INTERCONNECTING THE WHEELS THEREOF FOR ROTATION IN UNISON RELATIVE TO THE ARM, ANCHOR MEANS SECURED TO THE FREE END OF ONE OF SAID ARMS AND ENGAGEABLE WITH A SUPPORT FOR SAID LINKAGE, AND CONNECTING MEANS FOR SECURING A DRAWING ACCESSORY TO THE FREE END OF THE OTHER OF SAID ARMS; EACH 